How Does Space Affect the Human Body?
As you know, humanity has grown, formed, and evolved to the best of its ability on Earth. Accordingly, the human body is best adapted to exist in conditions peculiar to our planet. However, quite recently (consider it a second ago by evolutionary standards) we began to explore space, for which civilization has big plans. In space, however, radically different conditions, which sometimes have the most amazing effect on the human body.
So, we are used to living in an atmosphere consisting of about 78% nitrogen and 21% oxygen. The Earth’s magnetic field protects the planet and us from solar wind and cosmic radiation. In addition, we all have a clear sense of “top” and “bottom.” In space, all these (and many other) features do not exist.
Therefore, interesting things happen to the body of a person who has decided to go far away from Earth. Let’s talk about the five most noticeable effects in this article.
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#1 Space sickness
There is a marine disease, and there is a space one, or, more correctly, a “space adaptation syndrome.” This is the first thing that will happen to your body if you go into space. The complex of symptoms resembles seasickness, including nausea, vomiting, headaches, dizziness, and increased salivation with reduced appetite. It is believed that up to 90% of space travelers experience space sickness to one degree or another, and in the most unpleasant form it passes through about a third of the crew.
Space sickness is not contagious and is primarily caused by a violation of the interaction of the sensory systems of the body, and especially the vestibular system in zero gravity. The feeling of weightlessness leads to a discrepancy between what the eyes see and what is felt by the inner ear. This leads to dizziness and vomiting. By the way, parabolic flights to simulate weightlessness are often called “vomit comets.”
Some drugs can prevent the appearance of symptoms of space sickness. This is good news. The bad news is that such medications cause drowsiness, which is not very useful for the space crew. In addition, the body adapts itself to new conditions quite quickly. Usually, after one or two days, the body can compensate for the lack of gravity and gets used to it. It takes no more than a week to fully adapt.
It is curious that upon returning from space, many astronauts are waiting for the so-called gravitational disease with the same symptoms as the space adaptation syndrome. But in this case, everything goes even faster — in a few hours.
#2 A bad vision
Congratulations, you have reached space and recovered from a brief bout of space sickness. What’s next? And then there is a high probability of cosmic neuro-ocular syndrome (SANS). As in the case of space sickness, this ailment is also caused by weightlessness, only this time by its prolonged exposure.
The human body is 55-65% water. On Earth, due to gravity, the liquid tends down all the time. Our body has constantly evolved to compensate for this attraction. Complex circulation systems are used for a balanced distribution of various body fluids — from blood and lymph to bile and cerebrospinal fluid. All these systems “go crazy” when they begin to deal not with the usual terrestrial conditions, but with weightlessness.
The lack of downward thrust leads to the fact that the fluid begins to rush to the head. This increases the pressure on the eyes and changes the shape and location of the optic nerves, retina, and the eyeball itself. The pressure on the brain also increases, which also leads to structural changes in the visual system. Of course, all this can have an extremely negative effect on vision.
Space neuro-ocular syndrome is more dangerous than space sickness, as it can lead to significant consequences. In addition, it occurs in almost all astronauts who spend a lot of time on the space station. Scientists are actively studying the short- and long-term effects of SANS, but so far there is no prescription for this disease. All hope is only on the individual characteristics of the organism of a person being sent into space.
In space, with all the apparent emptiness, there is enough of one thing — radiation. Our Earth is constantly exposed to radiation from a variety of sources. Some of them, such as ultraviolet rays, penetrate the atmosphere and can cause sunburn. However, much more dangerous radiation is absorbed by the atmosphere or repelled by the magnetic field of the planet. We can observe the manifestation of the latter at extreme northern or southern latitudes in the form of auroras.
Orbital stations like the ISS are relatively close to Earth and at least partially protected from cosmic radiation. However, the magnetosphere of our planet will not be able to protect astronauts going to the moon or Mars from radiation. In space, radiation is constant and can pass through the walls of a spaceship, as well as through any organic matter.
When high-energy particles collide with human cells, they can cause physical damage to important molecules such as DNA. Often the body can repair damaged DNA, but sometimes this leads to cell death. In extreme cases, radiation can cause persistent mutations that will be transmitted to new cells during division.
All this leads to high cancer risk. Moreover, the longer a person is in space, the more “chances” he has to get cancer. Protecting astronauts from radiation is one of the priorities for future deep space missions. To date, this is one of the most serious obstacles to the exploration of the Moon, Mars, and other space objects.
#4 Crystal bones and flabby muscles
At first, glance, if you come to terms with the symptoms of space sickness, a short stay in weightlessness even seems useful. After all, in this state, a huge load is removed from the lower part of the body. A person does not need to stand and sit in the usual sense, that is, the body does not need to maintain the weight of the “ballast” upper body.
The load on the joints decreases, and it becomes much easier for the “tired” muscles of the legs and abdomen all the time. However, it’s not that simple. In the conditions of habitual gravity, the constant load on bones and muscles forces the body to restore and strengthen these tissues. Without exercise, bones begin to lose density, and muscles lose mass.
Since there are no permanent space settlements yet, it is assumed that any person who has flown into space will return to Earth at some point. The loss of bone and muscle mass can become a serious obstacle to the recovery of the body. To cope with this problem, astronauts constantly and actively train during long missions, artificially creating stress on joints and muscles.
In fact, this is not very profitable and convenient, because simulators take up a lot of literally precious space that could be given over to scientific equipment or payloads. But there are no other options yet, so simulators are the best solution to the problem of muscle and bone destruction at the moment.
#5 Eternal youth
Space sickness, threat of vision loss, radiation, mutations, joint destruction. It seems that nothing good awaits us in space. But still, you can find something useful for your health on a long journey.
In 2015, NASA sent astronaut Scott Kelly to the ISS for one year. At the same time, his twin brother Mark, also an astronaut, remained on Earth. Scientists have carefully studied and compared many parameters of the brothers before, during, and after the mission. And one effect turned out to be extremely unexpected — telomere elongation.
For clarity and understanding, scientists compare telomeres with plastic or metal tips on laces that prevent them from unraveling. So telomeres are such tips on DNA molecules. With each cell division, the telomeres become shorter and shorter, until eventually, they become so short that the cell can no longer divide and dies.
In theory, if you keep a sufficient length of telomeres, then the cell can divide close to an infinite number of times. And then the question arises, if not immortality, then at least a significant slowdown in the aging process of the body. Therefore, telomere lengthening methods are considered promising methods to combat aging.
So imagine the surprise of scientists who discovered that during the year spent in space, the telomeres in the cells of Scott Kelly’s body became longer, not shorter, like his brother on Earth. How and why this happened is still unclear. Perhaps someday we will get answers, but so far only the first steps are planned in this direction.
And one more small nuance. It seems that for “eternal youth” you will have to live in space all the time. Because a few months after returning to Earth, the astronaut’s telomeres returned to the default state and continued to decrease, like all earthlings.